One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,9)(8,10)(11,12)(13,14,19,23,20,24,18,25)(15,16,22,27,26,28,17,21)(5,6)(7,11)(8,10)(9,12)(13,15,20,26)(14,21,24,27)(16,23,28,25)(17,18,22,19)(2,4)(5,7)(6,9)(8,12)(10,11)(13,16)(14,22)(15,25)(17,24)(18,21)(19,27)(20,28)(23,26) involution — undirected(7,12)(9,11)(13,17,19,15,20,22,18,26)(14,21,23,16,24,27,25,28)(6,10)(9,11)(13,18,20,19)(14,23,24,25)(15,17,26,22)(16,27,28,21)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.